1. Technical Field
Various embodiments relate to a structure for reducing electromagnetic interference (EMI) and an electronic device using the same, and more particularly, to a 3D EMI suppression structure using a coplanar waveguide (CPW) and an electronic device having the same.
2. Related Art
As various electronic devices and instruments which operate an electronic system, such as computer devices, computer mainframes hand-held electronic devices, and mobile communication devices have spread and developed electronic operating systems inevitably receive EMI from outside sources or have internal EMI. The EMI source may be caused by another external electronic device or caused by an internal circuit of the electronic device. The EMI is divided into radiated EMI and conducted EMI. Since the radiated EMI is directly transmitted through an open space, the radiated EMI does not need to pass through a transmission medium. Thus the radiated EMI may be removed through a general method such as shielding or grounding. However, the conducted EMI transmits noise through a power or signal line. Thus, an internal line of the electronic device and an external line connected to the electronic device may cause conducted EMI for the signal line in the electronic device. Therefore, mutual interference may occur.
EMI is an unavoidable problem for electronic circuits which are designed to have high-speed digital lines. Particularly, common mode noise and differential signals for transmitting data at high speed during a signal transmission process may cause a serious problem. That is, EMI caused by the common mode noise may have an influence on a wireless communication system of an electronic device or instrument.
For example, FIG. 1 is a diagram for describing the interference of common mode noise in internal lines of an electronic device. FIG. 1 illustrates various interferences such as crosstalk 1, bending 2 length mismatch 3, and layout requirement 4. All of the interferences may have an influence on a wireless transmission system, and make it difficult for a wireless communication module to transmit/receive a wireless signal. Thus, the interferences need to be suppressed.
Conventionally, to suppress common mode noise a common mode choke has been installed in a circuit. However, a magnetic core having high magnetic permeability does not effectively maintain its high magnetic permeability at a high-frequency period, and thus it may lose magnetic permeability. Therefore, the common mode choke cannot be effectively applied to a structure for suppressing common mode noise during high-speed data transmission.